HSV1, cold sore,

Cold sores, which are sometimes called fever blisters, crop up on the lips or on the face near the mouth. In addition to being painful, they are unsightly. Cold sores are caused by the herpes simplex 1 virus that can lie in wait for months or years before re-appearing. Many readers have told us that they can side-step a cold sore by taking L-lysine at the first hint of one developing.

Will Taking L-Lysine Avert a Cold Sore?

Q. I have been taking L-lysine for years and I can’t remember my last cold sore. I had shingles one time many years ago and took L-lysine daily. It took one day for the pain to end and about two days for the rash to disappear.

I explain the efficacy of lysine this way: Herpes viruses cause both cold sores and shingles. They require the amino acid arginine to replicate itself. Somehow, the viruses recognize lysine as if it were arginine. The lysine prevents viral replication.

A. Your explanation is plausible, as supported by research on the herpes simplex virus 1 (Journal of Virology, June, 2009).  Herpes virus is reactivated by an enzyme,  lysine-specific demethylase 1 (Science Translational Medicine, Dec. 3, 2014). We don’t know how L-lysine affects that enzyme, but presumably there is some interaction.

Studies Are Lacking on Taking L-Lysine:

Sadly, there have been very few well-controlled trials involving L-lysine for cold sores. That has led to the conclusion that there is inadequate data to support the use of L-lysine to prevent or treat herpes infections (Cochrane Database of Systematic Reviews, Aug. 7, 2015). The Cochrane Review of the research found that drugs such as acyclovir and valacyclovir do seem to help prevent cold sores modestly.

Readers Offer Their Testimonials:

Despite the lack of clinical research, many readers have found L-lysine as helpful as you have. Ana wrote:

“Lysine has keeps me free of my yearly herpes outbreak for more than 10 years. I used to have an upper lip outbreak every summer for as long as I can remember.

“Around 1991 I found an article in a magazine about the effectiveness of lysine for herpes. I tried it the next time I had lesions. They went away in less time than usual.

Years after I read about taking 2 500 mg tablets every few hours at the first symptoms 10 times a day. I kept taking them for several days. It worked by reducing the size of the lesions and the healing time.

“I do not take them regularly, only when I have the symptoms. I did that for years and then I noticed that I was only getting a pinpoint-size pustule that would go away in two or three days.

“I always start the tablets if I feel the characteristic itching or tingling in my chin. I have told others about it and they have reported to me the same success. I always keep lysine on hand, just in case.”

LBP in Dallas reported:

“I, too, found that taking L-lysine the second I felt a tingling in my lip either greatly reduced the cold sore severity or, on rare occasions, stopped it in its tracks. But there seemed to be no way to absolutely prevent cold sores from trying to form. Over the course of my life (I’m 59), I just grew accustomed to watching for tell-tale signs and then ingesting mega-doses of lysine.

“A little over three years ago, I began taking 4,000 mg of vitamin D3 on a daily basis because of all I had read about vitamin D deficiency. A year and a half later, I noticed I had not had any cold sore symptoms AT ALL during that time and I connected it to the D3 I was taking. Today, more than three years later, I continue to be completely free of any outbreaks. I am convinced that the 4,000 mg of D3 daily is responsible and I’m curious as to whether others have experienced similar results.”

We don’t know whether vitamin D could have an effect on cold sores. Sun exposure can often trigger an outbreak.

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  1. Mai

    I have suffered from cold sores since age 16 when a parent gave me an innocent kiss – forgetting THEY had a cold sore. Now in my mid 50’s … two years ago I discovered L-lysine. WOW!!!! Every fall for my entire life I’ve suffered horrid cold sores 2 – 3 times a year that would puff up my lip … would take 2 – 3 weeks to heal.

    Now, when I am SICK and / or when the weather turns very cold .. I discovered that if I take 4000mg of lysine (spread out every 5 hours … at 1000mg dozes) …. and combine it with biotine (take 10000 mcg 2x a day) …

    result? The last THREE years .. I’ve had only ONE break out .. and it was so small no one could tell!! I’m sold. But the key is to take it BEFORFE you break out … so FIRST SIGN of sickness (flue / etc.) .. FIRST SIGN of extreme temperature drop .. for me (I live in Florida) a cold drop is 50 degrees … it’s all relative to what YOUR BODY ph balance / normal temperature balance is. I LOVE Lysine / biotin combo. Cold sore free practically!!

  2. Garden Girl

    Resently I had a bad case of shingles. My healthcare practioner told me to take L-lysine, 20,000 mg a day and to gradually back off as it got better. I found I had to also take vitamin C. If I didn’t, the itching would start up again mid afternoon and in the middle of the night – halfway between taking the L-lysine.

  3. Julie

    I’m so far impressed with no blister outbreaks for the past 3 months since I started taking lysine 1000mg at breakfast time. My triggers for the blisters over the last 40 years have generally been sun, wind, cold or stress. If I can get through the whole of this winter symptom-free, I will be strongly convinced that it works for me.

    I have generally experienced 4 to 6 outbreaks per year and to be free of them will be life changing. I haven’t changed my diet at all and still enjoy high arginine foods like oats and nuts.

  4. Marti

    I have found that ice or alcohol on a spot that is just starting will help stop it progressing further. Even if I let it go, and the small blister starts to form, I can then start treating it. The ice kills or slows the virus from developing, as will the alcohol. I simply rub an ice cube on the spot several times a day as many times as I think of it, or put alcohol on my finger or a cotton ball and apply that to the spot several times a day. This is only for surface skin lesions. I’ve used it on lip and nose region with good results.

  5. Paul
    Stoke on Trent

    Can my 14 year old daughter take L-lysine ?

    • David
      ONT, Canada

      I’ve been taking it since I was 12. Am 17 now and have no issues. When we talked to the doctor about my using it he didn’t have any objections.

  6. Gail

    I’ve used L-lysine for cold sores for years. I take 1,000 mg at breakfast as a preventive. If I should get the first sign of a cold sore, I increase the dose to 1,000 mg with each meal (3 times a day). I haven’t had one since I started taking one a day, though. I nearly always have oatmeal for breakfast, which is higher in arginine than lysine, so I figure that’s the best time to take it.

    One time I did an experiment and didn’t take lysine, and the cold sore was quite painful and lasted for weeks. Taking large doses at the first sign does the trick, but I recently read that preventing an outbreak by taking some each day was better. It seems to be working for me!

  7. Elaine
    Concord NC

    I’m a firm believer in using lysine to ward off cold sores. I used to get bad ones but have learned to start taking lysine when I feel the initial tingle of a developing cold sores. It prevents the blisters from forming!!

  8. PattyPR

    I take Lysine for canker sores in the mouth in addition to cold sores if they flare up. Once or twice per year I get a painful “pimple”, which I think is really a cold sore, on the side of my nose near to nostril. Lysine taken orally, and vitamin E applied topically, seem to cure it far more quickly than no treatment.

    Rarely, I get a persistent crack where top and bottom lips meet. I saw data long ago that this was not a herpes cold sore, but a different virus. I cured that on two different occasions, years apart, by keeping Vitamin E oil on it for a few days.

  9. Sue
    New York City

    Once I discovered L-Lysine for cold sores, I have pretty much “cured” myself of them. I still get one every few years, but as long as I start taking L-Lysine as soon as I feel the tingle of an oncoming cold sore, I halt the cold sore in its progress. It will still continue through its natural “course”, but much quicker and with hardly any pain or other side effects. Most people won’t notice you have anything.

    I have heard of friends who take just a small amount of L-Lysine when they have an outbreak, and it works, too. But now I take massive doses because I’m paranoid and don’t want to get the sore. (I take 2000mg several times a day for first 2 to 3 days, then take less after that.) I took Zovirax for cold sores for a year and it greatly decreased in its effectiveness. It stopped working pretty much. But now with L-Lysine I never have a full blown sore. And I carry L-Lysine when I travel, just so I can catch it when I need to – which should always be as fast as you can. I usually get it within 15 min., but if you wait a bit longer, it will still heal the cold sore much faster than if you had done nothing – or taken Zovirax. So it’s still worth taking, even if you can’t get it right away.

    I too got shingles but got rid of them in a week and a half with a combination of natural therapies, one of which was L-Lysine. Who knows what worked for me, but I’m just glad one, or some, of the things I did healed the shingles.

    If anyone would like my shingles protocol, I’d be happy to send it.

  10. Don M.

    I used to get cold sores very often. I started taking L-Lysine daily and now get 1 every 2 years. It only last a day and is not painful.

    • Grace
      United States

      Hi do you take it everyday? I’m going to go buy l lysine right now but I don’t know if It’s okay to take everyday or not. Thanks

  11. Kiki

    Since I began taking L-lysine, maybe thirty years ago, I have not had a single cold sore. However, I still have a genital herpes outbreak once in a while. I get the blister about two inches above my anus, between my “cheeks” instead of nearer my genitals. I am female and have never had anal sex. My mother had the same aberrant pathway herpes.

  12. Barbara

    Does Lysine increase blood pressure?

  13. Abbey
    Cary, NC

    I had my first cold sore in my 50’s. I now get them sometimes when I am out in the sun, cold or wind for long periods. That is pretty often often as I am a gardener. I have noticed that I will have an outbreak with certainty if I rub my lips or lick them a lot. I have also found that I will NEVER get them if I keep putting a good lotion on my lips and keep them moist. Even if I forget and end up with a cold sore, if I apply the lotion several times a day to the sore, it is much smaller and lasts half the time. I begin as soon as I feel the tingling. I have also tried salves made for cold sores and they work far less well and are expensive. Besides, the lotion is readily available and usually on hand. I find Vaseline Intensive care works the best. I know that glycerine is toxic to nerve tissue. Perhaps the glycerine in the lotion creates a hostile environment for the virus, which resides in nerves. Never spread the lotion elsewhere after applying and be sure to wash your hand thoroughly. The virus can be spread and can infect your eyes.

  14. Sue

    I too take L-lysine. I used to get horrible..what we call fever blisters on my lip and under my nose. A woman that my husband worked with saw me and told him to tell me to try L-lysine. I did and wow did it work. If I even feel a tingle, I start the L-lysine.

    I wish someone would have told my parents about this when I was a kid. The fever blisters didn’t always hurt but I was always self conscious about them.

  15. Susan Heil

    I have been taking lysine for years and when and if I get a cold sore, the duration of it is very short and the cold sore is so minute that nobody else can see it. My husband now takes lysine and he says the same thing. We each take one daily,

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